2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/106495A gauge-invariant formalism is presented for the practical treatment of photo- and electroproduction of pseudoscalar mesons off nucleons that allows an explicit incorporation of hadronic final-state interactions. The semi-phenomenological approach is based on a field theory developed by one of the authors. It generalizes an earlier approach by allowing for systematic improvement of approximations in a controlled manner. The practical feasibility is illustrated by applying the lowest-order result to the photoproduction of both neutral and charged pions.Plenary talk given at the N*2005 Workshop (Oct. 2005, Tallahassee, FL); to appear in the Proceedings (to be publ. by WorldScientific)Nuclear Theorytext